The present invention is generally related to engine controllers and, more particularly, is related to systems and methods for active control of surge in compressors, such as axial and centrifugal compressors.
The design and operation of jet engines are faced with many challenges that limit the operating range of those engines. Among those challenges are aerodynamic phenomena that occur in the compression system such as rotating stall and surge. Rotating stall manifests itself as a region of severely reduced flow that rotates at a fraction of the compressor rotational speed and causes a drop in performance. Surge is a pumping oscillation that can cause flameout and engine damage.
Due to the importance of these phenomena, considerable effort in compression system studies has been focused primarily on the design and implementation of active control schemes to ensure stable operation of the compression system over a wide range of operating conditions. However, those schemes, in their majority, are based on sensing after those phenomena have occurred and then taking appropriate control action. But the severity of those phenomena and their impact on the engine performance make it highly desirable to have a controller that is able to avoid the operation of the compressor in a region where the compressor is susceptible to those phenomena.
The present invention provides methods and systems for potentially avoiding a surge condition.
Briefly described, one embodiment of the system comprises a compressor, a combustor, a control computer, and a transducer. The transducer, which is located in the compressor, provides a pressure signal to the control computer. The control computer uses the pressure signal to proactively control a device, such as a bleed air valve or fuel valve, to avoid a surge condition in the compressor.
The present invention can also be viewed as providing a method for active control of surge in a compressor. In this regard, one embodiment of such a method, can be broadly summarized as including: detecting precursor information of the compressor; and controlling the compressor based on the precursor information to avoid a surge condition in the compressor.
One embodiment of the control scheme for the present invention uses a real-time observer for on-line identification of magnitude and frequency of dominant precursor waves. The observer outputs feed into a fuzzy logic control scheme, and the identified frequency and amplitude of the precursors are used to actuate devices, such as a bleed valve and/or a fuel valve, for active control of compressor surge.
Other systems, methods, features, and advantages of the present invention will be or become apparent to one with skill in the art upon examination of the following drawings and detailed description. It is intended that all such additional systems, methods, features, and advantages be included within this description, be within the scope of the present invention, and be protected by the accompanying claims.